Active Ethernet is one popular way to deliver massive amounts of bandwidth to subscribers over fiber and is a major contender for Fiber to the Home (FTTH) based broadband Internet rollouts.  In the US, it is more popular with the smaller telcos than with the larger ones.

Active Ethernet competes with Passive Optical Network in all it various flavors, which include Ethernet PON or EPON, 10G EPON, Broadband PON or BPON, Gigabit PON or GPON, and Wave Division Multiplex PON or WDM PON. Another very similar broadband access technology is called Point-to-Point (P2P) Ethernet or Active Fiber. The difference between Active Ethernet and Active Fiber is that Active Fiber has no switching gear outside of the Central Office (CO or wire center).

Active Ethernet Network

The essentials of an Active Ethernet network are shown in the diagram below.  Ethernet aggregation equipment is installed in the CO and in the OutSide Plant (OSP).  An Ethernet Optical Network Terminal (ONT) is installed at each customer premises.  The Ethernet aggregation device that connects directly to ONTs is a temperature-hardened Ethernet switch and called the Optical Line Terminal (OLT).

Active Ethernet Standards

Active Ethernet is specified in IEEE (US) standard 802.3ah for Ethernet in the First Mile.

Disadvantages of Active Ethernet

The name indicates a disadvantage in that “active” electronics must be deployed in the outside plant (OSP), and OSP electronics are more expensive to deploy and maintain than CO electronics. This is one of the advantages of PON, but at the same time PON access bandwidth is shared amongst all the subscribers served by a single splitter.

Active Ethernet imposes the cost of a network transceiver dedicated to each subscriber. The advantage of having a separate network transceiver dedicated to each subscriber comes at the cost of proliferation of one of the most expensive components in an optical broadband access network. An Active Ethernet access network will have roughly two times the optical transceivers of a Passive Optical Network.

Advantages of Active Ethernet

Active Ethernet is easier to manage. A network transceiver (in the ONT)  is dedicated to each subscriber so that the carrier has an unhindered view of each subscriber’s dedicated equipment.

Active Ethernet is a relatively mature technology with a variety of equipment choices. This give carriers a choice of network and subscriber equipment. Since the interfaces are standardized, a carrier even has a choice of deploying a multi-vendor broadband access network.

With Active Ethernet, sharing of bandwidth happens only on the uplinks to the aggregation equipment. Its key advantage is that tremendous bandwidth is available directly and unshared to each subscriber, at least 100Mbps and perhaps 1Gbps on each Optical Network Terminal. Active Ethernet is one of the most future proof access architectures.

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